/*
 * PaymentDAO.java 
 *
 * Created on March 5, 2007, 4:17 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package edu.byu.isys413.jjenkins.data;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;

 /**
 * This class contains methods to create, read, update and delete the 
 * payment Object. It also contains methods to read an object by
 * serveral different criteria. All interaction between the object 
 * and the database is done through this class. 
 * 
 * @author      Jeff Jenkins
 * @version     1.0
 * 
 */
public class PaymentDAO {
    
    private static PaymentDAO instance = null;
    
    
    /** Creates a new instance of PaymentDAO */
    private PaymentDAO() {
    }
    
        /* This method implements the singleton pattern. It insures that only
         * on instance of PaymentDAO exists
         *
         * @return: PaymentDAO instance */
    
    public static synchronized PaymentDAO getInstance() {
        if (instance == null) {
            instance = new PaymentDAO();
        }
        return instance;
    }
    
    /* This method creates a new PaymetBO with a unique QUID, puts the interest
     * in cache, and then returns it to the calling method.
     *
     * @return: PaymentBO: interest
     * @throws: DataException
     */
    
    public PaymentBO create() throws DataException {
        try {
            
            String id = GUID.generate();
            PaymentBO object = new PaymentBO();
            object.setId(id);
            Cache.getInstance().put(object.getId(), object);
            return object;
        } catch (Exception e) {
            throw new DataException("Could not create GUID", e);
        }
        
    }
    
    
    /**
     * This is the public read statement.  It loads an existing record
     * from the database.
     *
     * @Par: String: id
     * @Return: PaymentBO
     * @Throws: DataException
     */
    public synchronized PaymentBO read(String id) throws DataException {
        
        // Checks to see if the item is in cache
        Cache cache = Cache.getInstance();
        PaymentBO object = (PaymentBO)cache.get(id);
        try {
            
            // Gets connection
            ConnectionPool connPool = ConnectionPool.getInstance();
            Connection conn = connPool.get();
            
            // If the item is not in cache a connection is checked out and
            // The item is read from the database.
            if(object == null){
                try {
                    //reads in object
                    object = read(id, conn);
                    
                }catch (SQLException e) {
                    conn.rollback();
                    throw new DataException("Could not retrieve record for id=" + id, e);
                }
            }
            
            // connection committs and is returned.
            conn.commit();
            connPool.release(conn);
            
            
            
        } catch (SQLException e) {
            throw new DataException("Could not retrieve record for id=" + id, e);
        } catch (DataException e) {
            throw new DataException("Could not retrieve record for id=" + id, e);
        } catch (ConnectionPoolException e) {
            throw new DataException("Could not retrieve record for id=" + id, e);
        }
        
        // Return object
        return object;
    }
    
    /**
     *  This is a package method that is called by the public read (above) or
     *  by another DAO.  Either way we already have a connection to the database
     *  to use.  The user (controller) code never calls this one directly, since
     *  it can't know about Connection objects or SQLExceptions.
     *
     *  @Par: String: id, Connection conn
     *  @Return: PaymentBO
     *  @throws: DataException, SQLException
     */
    synchronized PaymentBO read(String id, Connection conn) throws SQLException, DataException {
        
        
        // Checks to see if the item is in cache
        Cache cache = Cache.getInstance();
        PaymentBO object = (PaymentBO)cache.get(id);
        
        // Quieries that database
        if(object == null){
            
            PreparedStatement pstmt = conn.prepareStatement("SELECT * FROM payment WHERE payment_id = ?");
            pstmt.setString(1, id);
            pstmt.execute();
            ResultSet rs = pstmt.getResultSet();
            
            if (rs.next()) {
                object = new PaymentBO();
                object.setId(rs.getString("payment_id"));
                object.setAmount(rs.getDouble("amount"));
                object.setType(rs.getString("payment_type"));
                
                
                
                // Sets already in database
                object.setObjectAlreadyInDB(true);
                
                // adds to cache
                cache.put(object.getId(), object);
                
            }else{
                throw new DataException("Object was not found in the database.");
            }
        }
        
        
        // returns customer
        return object;
    }
    
    /**
     * This is the public save method.  It is what is called when
     * the user (controller) code wants to save or update an object
     * into the database.
     *
     * @par PaymentBO object
     * @throws DataExcpetion
     */
    public synchronized void save(PaymentBO object) throws DataException {
        try {
            
            
            // retrieve a database connection from the pool
            ConnectionPool connPool = ConnectionPool.getInstance();
            
            Connection conn = connPool.get();
            
            
            try {
                
                // Saves Interest
                save(object, conn);
                
            }catch (SQLException e) {
                conn.rollback();
                throw new DataException("Could not save record for" + object.getId(), e);
            }
            
            // connection committs and is returned.
            conn.commit();
            connPool.release(conn);
            
            // touch the cache for the object
            Cache.getInstance().touch(object.getId());
            
            
            
        } catch (DataException e) {
            throw new DataException("Could not save record for" + object.getId(), e);
        } catch (ConnectionPoolException e) {
            throw new DataException("Could not save record for" + object.getId(), e);
        } catch (SQLException e) {
            throw new DataException("Could not save record for" + object.getId(), e);
        }
        
        
    }
    
    /**
     *  This is a package method that is called by the public save (above) or
     *  by another DAO.  Either way we already have a connection to the database
     *  to use.  The user (controller) code never calls this one directly, since
     *  it can't know about Connection objects or SQLExceptions.
     *
     *  By having other DAOs call this save method (rather than update or
     *  insert below, each DAO in a chained save (like the CustomerDAO calling
     *  MembershipDAO calling InterestDAO save chain) can independently decide
     *  whether to udpate or insert the BO it's saving.  That's why I made
     *  update and insert private rather than package level -- if you call
     *  them directly from another DAO, this DAO can't decide whether it's
     *  object needs to be inserted or updated.
     *
     *  @par: PaymentBO, Connection conn
     *  @throws: SQLException, DataException
     */
    synchronized void save(PaymentBO object, Connection conn) throws SQLException, DataException {
        
        // check the dirty flag in the object.  if it is dirty,
        // run update or insert
        if (object.isDirty()) {
            if (object.isObjectAlreadyInDB()) {
                update(object, conn);
            }else{
                insert(object, conn);
            }
            object.setDirty(false);
        }
        
        
        
    }
    
    /**
     * This method is really a part of save(bo, conn) above.  It could be
     * embedded directly in it, but I've separated it into it's own method
     * to isolate the SQL udpate statement and make it more readable.  But
     * logically, it's really just a part of save.
     *
     * @Par PaymentBO object
     */
    private synchronized void update(PaymentBO object, Connection conn) throws SQLException, DataException {
        
        PreparedStatement pstmt = conn.prepareStatement("UPDATE payment SET payment_id = ?, amount = ?, payment_type = ?, transaction_id = ? WHERE payment_id = ?");
        pstmt.setString(1, object.getId());
        pstmt.setDouble(2, object.getAmount());
        pstmt.setString(3, object.getType());
        pstmt.setString(4, object.getTransaction().getId());
        pstmt.setString(5, object.getId());
        
        
        pstmt.execute();
        
    }
    
    /**
     * This method is really a part of save(bo, conn) above.  It could be
     * embedded directly in it, but I've separated it into it's own method
     * to isolate the SQL insert statement and make it more readable.  But
     * logically, it's really just a part of save.
     *
     * @Par PaymentBO object
     */
    private synchronized void insert(PaymentBO object, Connection conn) throws SQLException, DataException {
        
        // Creates prepared statemetn
        PreparedStatement pstmt = conn.prepareStatement("INSERT INTO payment VALUES(?, ?, ?, ?)");
        pstmt.setString(1, object.getId());
        pstmt.setDouble(2, object.getAmount());
        pstmt.setString(3, object.getType());
        pstmt.setString(4, object.getTransaction().getId());
        
        //Executes prepated statement
        pstmt.execute();
        
        //Sets already in database true
        object.setObjectAlreadyInDB(true);
        
    }
    
    
    /* We intentionally do not allow a PaymentBO object to be deleted because
     * it could mess up relationships in the database. Obmitting the delete
     * also prevents fraud. */
    
    public synchronized void delete(CustomerBO customer)throws DataException{
    /* We intentionally do not allow a PaymentBO object to be deleted because
     * it could mess up relationships in the database. Obmitting the delete
     * also prevents fraud. */
        throw new DataException("You can not delete a PaymentBO");
    }
    
    /** this method reads a payment by the transaction id
     *  @par: string, connection*/
    
    public PaymentBO readByTransaction(String id, Connection conn) throws SQLException, DataException{
        try{
            
            PaymentBO object = null;
            
            PreparedStatement pstmt = conn.prepareStatement("SELECT payment_id FROM payment WHERE transaction_id = ?");
            pstmt.setString(1, id);
            pstmt.execute();
            ResultSet rs = pstmt.getResultSet();
            
            if (rs.next()) {
                object = read(rs.getString("payment_id"), conn);
            }
            return object;
            
        }catch (SQLException e) {
            conn.rollback();
            throw new DataException("Error reading record by customer id", e);
        }
    }
    
}
